Chronic idiopathic urticaria (CIU) is no longer idiopathic: time for an update

During recent years our knowledge of the aetiology and pathogenesis of urticaria has advanced considerably allowing us to better characterize urticaria subtypes. However, although the classification of urticaria has undergone some revisions during this time (1), authors still use different names for the same type of urticaria, which has implications for comparing study outcomes and drug licensing. Consequently, there is an urgent need for a harmonized and universally accepted nomenclature and classification of urticaria and to avoid the routine use of the outdated aetiological term, chronic idiopathic urticaria (CIU).